DESCRIPTION (From the applicant's abstract): Recently,alpha-synuclein has been identified as a major component of Lewy bodies, the intracellular inclusions that are a pathological hallmark of Parkinson's disease (PD). Our goals in this proposal are to test the hypothesis that a critical step in Parkinson's disease is the aggregation of alpha-synuclein, which leads to the formation of Lewy Bodies and subsequently to neuronal death. Specifically we will determine the molecular basis for alpha-synuclein aggregation and investigate potential inhibitors of alpha-syouclein aggregation. Our preliminary results have revealed a number of factors that lead to a confonnational change in alpha synuclein at neutral pH, and also to aggregation and fibril formation. We plan a systematic characterization of the biophysical properties of alpha-synuclein to determine if there is a correlation between its conformation and its propensity to aggregate, with both wild type and mutant alpha-synucleins. We will investigate whether various factors associated with PD, for example, metal ions and pesticides, enhance the aggregation of alpha-synuclein. Details of the aggregation process will be studied to elucidate the molecular mechanism of aggregation and fibril formation. We will screen a series of peptides and small molecules for inhibitory effects on alpha-synuclein aggregation. These experiments represent critical steps towards elucidating the role of alpha-synuclein in Parkinson's disease. We expect to learn the potential role of various factors, ranging from environmental contaminants to the concentration of alpha-synuclein, in triggering fibril formation. Further, we anticipate fnding inhibitors which may lay the groundwork for potential therapeutic approaches. Techniques to be used include various biophysical/biochemical methods, such as attenuated total reflectance FTIR to analyze the conformaffonal state of aggregated alpha-synuclein, atomic force and electron microscopy to image the aggregates, and kinetic methods to monitor the rate of formation of fibrils.